To find sample size, use the following equation, where n = sample size, za/2 = the critical value, p = probability of success, q = probability of failure, and E = margin of error.

$n=\frac{(z_{\frac{\alpha }{2} })^{2} *p*q }{E^2}$

The values that are given are p = 0.84 and E = 0.03.

You can solve for the critical value which is equal to the z-score of (1 - confidence level)/2. Use the calculator function of invNorm to find the z-score. The value will given with a negative sign, but you can ignore that.

(1 - 0.9) = 0.1/2 = 0.05

invNorm(0.05, 0, 1) = 1.645

You can also solve for q which is 1 - p. For this problem q = 1 - 0.84 = 0.16

Plug the values into the equation and solve for n.

$n =\frac{(1.645)^2*0.84*0.16}{(0.03)^2}\\n= 404.0997333$

Round up to the next number, giving you 405.

6 0

2 years ago

Nasir and Seif began with an equal number of Skittles. Nasir ate 10 Skittles, and Seif ate 6. Now the ratio of Nasir's Skittles

Finger [1]

X=Amount of skittles at the start.
Nasir ate 10 skittles and Seif ate 6 skittles so the number of skittles they had(x) - how many they both ate equals : 2/3;

(x-10)/(x-6)=2/3
3(x-10)=2(x-6)
3x-30=2x-12
x-30=-12
x=18

They each started with 18 skilttles.

7 0

2 years ago